U.S. Pat. No. 4,304,869, discloses an apparatus for rupturing a sealed frangible container. The frangible container is enclosed in an elongated tubular member having an annular space of decreasing dimension. The frangible container, e.g. a vial, contains a biological indicator for the sterilization process. The device is utilized to measure the effectiveness of steam or gas sterilization process. The tubular member is enclosed at each end. The device is fitted together by insertion of an end cap which can support the frangible container into a flanged section. Sterilant passes into the tubular member between the flanged portion and the cap which presents a tortuous path for the sterilant which may be steam or a gas.
U.S. Pat. No. 4,461,837, discloses a biological system for use in sterilization processes. A container is provided to enclose a frangible vial containing a biological indicator. The sterilant gas gains access to the indicator comprising spore strips by passing through the annulus formed by the outer dimension of the tubular container and a cap fitted at one end. The sterilant fluid communication between the exterior and interior of the container is described as taking place along a tortuous path because fluid traversing the path must negotiate at least two 90.degree. turns in order to gain access to the interior of the container.
U.S. Pat. No. 4,914,034, discloses a disposable biological test pack for monitoring steam and ethylene oxide sterilization processes. The test pack comprises a fiberboard housing which includes two end sections and a midsection. Each end section includes an outer tube and a longer inner tube. The open end of the outer tubes abut the opposing ends of the midsection to define a seam or gap. The inner tube extends past the seam and telescopes into the midsection. The seam and the close tolerance between the inner tube and midsection provide a tortuous path for entry of the sterilant into the interior of the housing. The tortuous path has a moisture absorbent surfaced and is dimensioned to promote intimate contact between the sterilant and absorbent surface. A second path of entry is provided for ethylene oxide sterilization processes only. In the ethylene oxide process the ETO reaches the biological indicator via a second tortuous path, and to a lesser extent through the first tortuous path.
U.S. Pat. No. 4,591,566, discloses a biological indicator probe for steam sterilization systems. The probe comprises a rod of heat resistant material, i.e., polysulphone resin, having an end chamber (test probe element) closable by a rotatable sleeve. The test probe element is made of the same material as the rod. The test probe element is adapted to accept a test vial containing the biological indicator through closable windows. The test vial is exposed to the steam and high temperature of the autoclave through the windows.
U.S. Pat. No. 4,839,291, discloses a disposable biological indicator test pack for monitoring steam and ethylene oxide sterilization processes. The test pack includes a fiber board housing for a biological indicator comprising an outer tube and a shorter inner tube. The outer tube has upper and lower portions which define a seam or gap at their adjoining ends. The inner tube extends past the seam and telescopes into the upper and lower portions of the outer tube. The seam and the close tolerance between the inner tube and the outer tube prove a tortuous path for entry of sterilant into the interior of the housing. The tortuous path has a moisture absorbing surface and is dimensioned to promote intimate contact between the sterilant and the absorbent surface. A hole covered by an optionally removable tab is provided at the end of the upper portion of the outer tube for use in monitoring ethylene oxide sterilization processes. The vial containing the biological indicator is enclosed in ampule having a cap. The space between the cap and the outer ampule wall provides an additional tortuous path for entry of sterilant into the biological indicator.
European Patent Application No. 0 255 229 A2 discloses a steam sterilization test pack comprising a plastic tube having a steam sensitive sterilization card and a biological indicator therein. The tube has end caps both of which have centrally located apertures. The caps have an inside diameter slightly larger than the outside diameter of the tube. The spacing between the cap and tube provide a circuitous path for the entry of steam.
European Patent Application No. 0 419 282 A1 discloses a disposable test pack for steam or gas sterilization. The test pack comprises a container filled with porous packing material. The packing material challenges the penetration of the sterilant by providing a restricted pathway which acts to impede the flow of sterilant through the test pack. The test pack can contain either a biological or chemical indicator or both to detect the efficacy of the sterilization process.
Whether used for steam or ethylene oxide process monitoring, the devices of the prior art require a tortuous path, provided either by geometric design of the device or by packing, for the entry of sterilant into the test chamber. Generally the indicator is a biological indicator, though chemical indicators are disclosed.
The Association for the Advancement of Medical Instrumentation (AAMI) has developed a protocol for testing the ETO sterilization process which comprises the utilization of a large plastic syringe into which a biological indicator can be placed. The syringe has an elongated constricted element, integral with the syringe at one end in place of a needle, and a plunger at the end remote to the constricted element. After the indicator is placed into the syringe the plunger is put into place, thereby leaving only the elongated element as an entry way for the ETO. The device is wrapped in a large towel and placed into the sterilizer for the purpose of monitoring the sterilization process.
This procedure has been modified by replacing the towel by a fiber board cylinder which is dimensioned to fit snugly over the syringe body. The cylinder serves as a heat sink as well as absorbing ETO and moisture to delay the kill rate of the spores within the biological monitor, usually spore strips having specific resistant strains of microbes deposited thereon.
U.S. Pat. No. 4,138,216, discloses a chemical type ethylene oxide indicator. The device comprises a wick enclosed in an ethylene oxide (ETO) impervious envelope having the wick exposed at one end. The wick is impregnated with a magnesium halide which is reactive with ETO to form a base, the presence of which is detected by a pH sensitive dye incorporated into the wick.
In use the chemical indicator is enclosed in a pack of material which requires sterilization. The pack offers resistance to the entry of ethylene oxide. Hence the indicator will indicate the quality of the process to which the material to be sterilized is exposed. Examination of the chemical indicator requires opening the pack to view it, thereby exposing the sterilized contents to potentially septic conditions. It is of value to be able to monitor the effectiveness of the sterilization process without the need to open a sterilized package. Use of the chemical process monitor of the '216 patent without a pack results in erroneous results in that the device is designed to be utilized in a pack, and indicate sterilization after adequate exposure to ETO for the proper time under appropriate humidity conditions. What is needed is a method for utilizing the chemical process monitor without enclosing it in a pack of material requiring sterilization, thereby permitting ready access to the monitor in order to evaluate the efficacy of the sterilization process.